1. Field of the Invention
The invention relates to a medical device having at least two units for monitoring and/or controlling thereof, and two communications buses. The units include at least one computer with a microprocessor, and at least one unit having a second computer with a second microprocessor, with each of the computers being attached to either the first or the second communications bus. The invention is also directed to a method for the programming, the implementation of the test sequences, the diagnosis and maintenance of such a device.
2. Description of the Related Art
Such medical devices often exhibit a computer architecture with two communications buses. Such a computer architecture is generally appropriate when, in addition to the action computer system, a medical device needs for safety requirements an auxiliary computer system that monitors independently the operating mode of the action computer system and in the event of an emergency can induce a safer state of the device.
Such a device is described in the German patent DE 198 49 787 C1, to whose publication reference is explicitly made here. In this patent application a hemodialysis unit is described that—based on the computer system—exhibits a modular construction. An operating unit, a hydraulic unit and a functional unit respectively include one action and one auxiliary computer each.
The action computers are connected by means of an action bus; the auxiliary computers, by means of an auxiliary bus. Furthermore, communication between the action and the auxiliary computer within one unit is possible.
The auxiliary computer of the operating unit of the hemodialysis unit exhibits an external interface. By means of this interface it is possible to conduct by means of an external device the programming, the implementation of test sequences, the diagnosis and the maintenance of all computers of the hemodialysis unit. However, the computer architecture of this device exhibits the following drawback. Whereas the auxiliary computers can be addressed relatively easily by means of the auxiliary bus, the action computers can be addressed only by means of the modular internal interface between an action computer and the related auxiliary computer. Not until after such a transition can the data be sent via the action bus. The internal computer connection turns out to be a bottleneck with respect to the data transfer rate, resulting in unnecessary long periods for data communications.
However, there are also objections of a different kind against modular internal communication. If data are to be transferred to an action computer, then it is necessary for the aforementioned reasons to use at least in one unit the modular internal interface between an action computer and the related auxiliary computer. Hence, several computers are always tied into the data transfer operation. Furthermore, each computer must have additional software to even handle the data transfer. In this respect the operation is altogether time consuming and error prone.
The DE-A-37 36 712 describes a similar modular-like dialysis unit, which provides a hierarchical computer structure. All control processors are connected to a main control processor, and all monitor processors are connected to a main monitor processor. The main processors in turn are interconnected.
The EP 0 491 183 A1 discloses a device, wherein the driver and receiver units are connected between a main data bus and an internal bus. To access the internal bus from the main data bus for test purposes, there are bidirectional logic means, which exhibit, however, a complicated design.
The EP 0 306 211 A2 describes a very expensive, synchronized twin computer system. To coordinate the cycles and the parallel running programs, there is data communications between two computer systems via its own controller.
The DE 40 22 365 A1 proposes a data transfer system, wherein an address bus and a data bus between a microprocessor and a data memory can be interrupted for the purpose of more efficient direct memory access (DMA).
An external device for diagnosis of an integrated switching circuit by means of a bus system is the subject matter of the GB 2 282 244 A.